Figure 9b – Outdoor Aiming and Tracking Setup
The beam shape on the target is shown in Figure 9c for the unfocused beam and focused beam (the target squares are 1 ft. on edge). Focusing is accomplished by slightly increasing the
membrane into the parabolic shape required to focus the beam.
The differential pressure required
is small (of the order of 0.1 inches of water).
The area of the bright spot of the focused beam on
the target is 2.05 sq ft.
If the area of the bright spot is divided into the total area of the mirror
(18.85 sq ft), a geometric concentration factor of 8.7 is achieved. The video that this report has a sequence in which the beam is taken from unfocused to focused.
The ability of the heliostat to maintain the focused beam shape over a long period of time (hours) could not be tested due to a slow air leakage problem with the prototype. However, there is no reason to believe this could not be easily accomplished in a production application.
November 24, 2002